Shoe with reduced length innersole and smooth transition in flexibility

ABSTRACT

A shoe having enhanced flexibility is disclosed, wherein there is a reduction in the stiffness of the shoe in proximity to the flexline. The shoe has a shortened innersole and a reduction in innersole stiffening material toward the toe end of the shoe. The innersole may include cutouts that reduce the stiffness of the innersole in proximity to the flexline. A method of manufacturing such shoes is also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional Patent Application No. 60/894,952 filed Mar. 15, 2007 which is fully incorporated herein by reference.

FIELD OF THE INVENTION

The present application relates to a flexible shoe, and method of manufacturing the same, and in particular, to a shoe having a reduced length innersole, wherein the innersole also is configured toward its shoe toe end so that in proximity of the flexline the innersole requires a substantially reduced force to bend the shoe.

BACKGROUND OF THE INVENTION

A fundamental criterion for shoes is the comfortableness of the shoes for the wearer. A second fundamental criterion for shoes is the style or decorative quality of the shoes. Appropriately combining these two criteria has been the goal of most shoe manufacturers. In many lines of shoes, comfort has taken a back seat to style. Thus, for example, women may wear stylish shoes to an event, and at some point in time during the event (e.g., when dancing commences), these women will remove their stylish shoes and dance barefooted due to the lack of comfort of their shoes.

Much of the discomfort of many such stylish shoes is due to their inflexibility, wherein the shoes do not comfortably flex along a curve extending between the first and fifth metatarsal heads of a user's foot. This curve or line is sometimes known in the art as the “flexline,” and is generally located where the primary bending occurs when a user walks.

For most shoes, such inflexibility along the flexline is a consequence of the structural features typically required to produce a shoe that has acceptable durability. In particular, most shoes have at least three layers of material making up the sole of each shoe manufactured. That is, there is: (1) an insole which contacts the user's foot, and which is preferably smooth and soft, (2) an external portion of the sole that contacts a surface being walked upon which is known as the “outer sole”, and is typically made up of a substantially more durable material than the insole, and (3) between the insole and the outer sole is one or more layers aggregately known as the “innersole”. The innersole typically provides the structural stiffness of a shoe so that it maintains its general form during use. For example, the innersole may contain a smoothly curved metal shank that extends from the heel of the shoe through at least the arch-supporting portion of the shoe for maintaining the shoe's form when being worn. Although the shank does not generally extend to the flexline, the innersole typically has an extent that is identical to that of the outer sole and the insole. Moreover, such innersoles are generally stiff even from the flexline to the toes. Such stiffness is generally required since the attaching of the insole to the outer sole may require such stiffness since in stitching the insole to the outer sole (together with a shoe top that covers and/or secures the user's foot to the insole) can necessitate a stiff innersole to effectively secure the stitching between these various layers. In many shoe embodiments, the innersole includes at least one layer of an extremely stiff fiberboard or cardboard that has a shank attached thereto or imbedded therein. Accordingly, the perceived stiffness of a shoe when walking may be substantially due to the stiffness of the innersole from generally the flexline to the toe tip of the shoe.

In U.S. Patent Application Publication 2007/0011918 published Jan. 8, 2007 and fully incorporated herein by reference, a shoe is disclosed wherein the innersole appears to be composed of two disconnected pieces. A first such piece extends from the heel of the shoe to an area just prior to the flexline, and a second piece is provided at the toe tip of the shoe for maintaining the shape and rigidity of the toe portion of the shoe. These two rigid innersole pieces are spaced apart such that there appears to be a reduced or no innersole across the width of the shoe where the ball of a user's foot and the flexline would be positioned when the user is walking in the shoe. Thus, it is purported that the shoe is more comfortable since it flexes more easily at the flexline than conventionally made shoes that have a stiff innersole extending the full length of the shoe. However, the innersole appears to extend at least 80% of the user's footprint within a properly sized shoe, thereby making at least certain types of shoes less flexible than the wearer would desire when walking, dancing, etc. Moreover, since the biomechanics of different users feet vary somewhat for the same shoe size, and since a user's feet generally do not abruptly change from the substantially inflexible heel and midfoot section to the more flexible forefoot section of a user's feet, the abrupt termination of the innersole can lead to potential instabilities of the user walking in such a shoe.

An additional example of a shoe construction technique that provides a presumably more flexible shoe is disclosed in U.S. Pat. No. 4,835,884 issued Jun. 6, 1989 which is also fully incorporated by reference herein.

Accordingly, it would be desirable to have a shoe construction technique, wherein the resulting shoes are both more flexible and stable when walking, dancing, jogging, etc. In particular, it is desirable to provide lady's high heeled sandals that are both flexible to wear and substantially stable in the same manner as if the sandals were substantially more inflexible in the forefoot section of the sandals.

SUMMARY OF THE INVENTION

A shoe and shoe construction technique is provided wherein the innersole is reduced in length to enhance shoe flexibility having a first lengthwise portion extending from the shoe heel toward the flexline, and a second lengthwise portion extending from the first portion further toward the toe end of the shoe, and wherein the second portion includes a reduced width portion (more generally, a reduction in the quantity of innersole stiffening material) at the end of the innersole nearest to the toe area of the shoe. The length of the innersole is reduced in comparison to the length of sole of the shoe. For example, the innersole length may be between approximately 78% and 85% of the total length of the shoe sole (more precisely, 78% and 85% of the total length from the heel to the furthest opposite end of the insole where the user's foot is expected to reside in the shoe). However, an acceptable variation in the innersole length may be between 75% and 85% of the total length as identified above. Alternatively, the innersole may end substantially at the flexline of a user's foot, or within ½ to ¾ of an inch beyond such a flexline.

The reduced width portion is shaped so as to provide an intermediate amount of flexibility that allows for a smooth transition in the flexibility of the shoe from the substantially rigid heel and midfoot area to the very flexible portion of the forefoot portion of the shoe beyond the metatarsals of the user wearing the shoe. This reduced width portion extends in the shoe length direction for approximately 8%±1% of the length of the shoe, although variation between 6% and 10% may be acceptable in some embodiment. Additionally/alternatively, the innersole may include a first portion that extends from the heel of the shoe for approximately 70% to 77% of the length of the insole towards a toe area of the shoe, wherein the width of this first portion, throughout its length, is substantially coincident with an adjacent portion of the insole (e.g., within 3% to 4% of the width of the corresponding overlaid portion of the insole). However, in some embodiments this first portion may have an acceptable variation in length of between 65% and 78% of the total length of the shoe.

Since a shank extending lengthwise of the shoe along the first portion of the innersole terminates prior to a boundary between the first portion and the second portion of the innersole, the innersole now provides three or four distinct levels of flexibility/rigidity for the shoe. The first level, from the shoe heel to the termination of the shank is effectively inflexible and provides the structural support for the shoe. The second level, from the termination of the shank to the boundary between the first and second portions of the innersole, has a flexibility that would be considered conventional for a shoe. The third level, from the boundary (or transition) between the first and second portions to the end of this second portion towards shoe toe tip provides an additional more flexible area of the shoe (generally, commencing prior to the flexline). Finally, assuming the innersole does not extend the entire length of the shoe insole, a four level of even greater shoe flexibility is provided, wherein this four level extends from the end of the second portion (closest to the toe area) to the shoe toe tip.

The present disclosure is also directed to a method of manufacture of shoes according to the following steps:

-   -   (a) providing an insole, an outer sole for the shoe, and a foot         covering for securing the shoe to a user's foot;     -   (b) obtaining an innersole for the shoe, wherein the innersole         includes a first portion having a length that extends from a         heel for the shoe towards a distal end of the shoe, wherein         throughout the length, the first portion has a width         substantially coincident with a width of an insole for the shoe;         -   wherein the innersole includes a stiffening portion cut or             stamped from a substantially planar material for stiffening             the shoe, the stiffening portion including a first portion             having a length that extends from a heel portion of the shoe             towards a distal end of the shoe's length, wherein the first             portion has a width substantially coincident with the             insole's width throughout the length of the first portion,             and the first portion is for stiffening the shoe;         -   wherein the stiffening portion includes a second portion             extending from the first portion and toward the distal end,             wherein the second portion includes reduced quantity of             innersole stiffening material across the second portion's             corresponding innersole widths in comparison to the first             portion;         -   wherein the reduced quantity of material second portion             provides an intermediate flexibility between a rigidity of             the portion of the sole having the first portion, and a more             flexible portion of the sole extending beyond the innersole             to the toe area of the shoe; and     -   (c) affixing the innersole and at least one portion of the foot         covering between the insole and the outer sole of the shoe,         wherein the at least one portion of the foot covering is not         layered above or below the innersole.

Other features and benefits are disclosed in the description hereinbelow and the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a top view of the layers of a novel shoe sole 20.

FIG. 2 shows a sandal 24 constructed with the sole 20 illustrated in FIG. 1.

FIG. 3 shows a bottom view of the layers of a novel shoe sole 20.

FIGS. 4A-4D show alternative embodiments of innersoles 32R, 32.1R, 32.2L, and 32.3L according to the present disclosure.

FIG. 5 shows the high level steps that may be performed in manufacturing an sole 20 according to the present disclosure.

DETAILED DESCRIPTION

FIG. 1 shows a generally top view of the layers of the sole 20 a ladies' high heel sandal, wherein the sole 20 has its layers separated and offset from one another to more clearly illustrate the composition thereof. Note that the upper sandal strap(s) for securing the user's foot to the sole 20 is not shown, but such straps may be attached in any conventional technique once the layers of the shoe sole shown in FIG. 1 are combined to form the sole 20 of a sandal such as the sandal 24 is illustrated in FIG. 2.

Referring to FIGS. 1 and 2, the sole 20 of the shoe (i.e., the sandal 24) of FIG. 2 includes an insole 28 that contacts the user's foot, an innersole 32 that provides both stability and structural support for the user when wearing the shoe 24, and an outer sole 36 for contacting the ground when the user walks in the shoe.

Referring to FIG. 3, the bottom of the innersole 32 from the near the heel and extending towards the toe area 38 (e.g., the enclosed dashed area, FIGS. 1 and 3) of the sole 20 is shown. The innersole 32 includes a base 40 of cardboard or fiberboard that extends to and defines the perimeter or boundary defining the innersole. The innersole 32 further includes a shank 44 attached to the base 40. The shank 44 provides structural rigidity to the sole 20, and accordingly is typically made of metal such as steel although other materials such as various plastics may be used instead. In some embodiments, the shank 44 is provided in an insert within the base 40. The shank 40 extends from substantially the heel 48 of the sole (and the sandal 24, see FIG. 2) through the midfoot portion 52 of the sole 20 (and the sandal 24). In the present embodiment of the innersole 32, the innersole base 40 has a full insole width portion 56 having a width across the shoe that is coincident with the insole 28 from the heel 48 to approximately three-quarters of the length of the insole 28 towards the toe area 38 of the forefoot portion 60 (of the sole 20 and the sandal 24, FIG. 2), and more generally, between 65% and 78% of the total length of the shoe. In particular, as shown in FIG. 3, the full insole width portion 56 may be only slightly longer than the shank 44 (e.g., approximately one-eighth to one-quarter of an inch longer), although variations up to three eights or half of an inch may be acceptable. Extending beyond the full insole width portion 56 of the base 40 is an insole tongue 64 that has a reduced width in comparison to the corresponding adjacent portion of the insole 28 and the outer sole 36. In particular, the tongue 64 has a width that is reduced in comparison to the adjacent portions of the insole 28 and the outer sole 36 between which the tongue is sandwiched, and such width reduction is in a range of approximately 20% to 33% of the corresponding widths of the insole and outer sole, although variations between 15% and 35% may be acceptable. More particularly, for each width W (FIG. 3) of the tongue 64 along its length, the corresponding (i.e., coincident) widths W_(i) and W₀ for, respectively, the insole portion and the outer sole portion contacting the width W, the width W is approximately 20% to 33% shorter (more generally 15% to 35%). Moreover, reduction in tongue width occurs more on the outer walking edge of the innersole 32 than on the inner walking edge of the innersole so that when a user of the shoe 24 is walking, there may be approximately an equal amount the user's weight that is unsupported by the tongue 64 on either side beyond the width W of the tongue 64. In one embodiment, approximately 60% to 70% of the reduction in tongue width occurs on the outer walking edge of the innersole 32. Moreover, in preferred embodiments, when walking the user may not sense any variation to the insole contour due to the reduced tongue 64 width. The lack of user sensed insole contour variation may be due to increased thickness of the flexible insole 28 in innersole cutout areas, and/or due to increased thickness from the attachment of, e.g., the sandal straps 74 as described hereinbelow.

In some embodiments, the tongue 64 extends between approximately three-quarters of an inch to one and three-quarters of an inch beyond the full width extent of the base 40. The reduced width of the tongue 64 provides a transitional area in the sole 20 of the shoe 24 from the essentially rigid midfoot 52 to the much more flexible forefoot 60. That is, the reduced width of the tongue 64 results in the portion of the sole 20 corresponding thereto having an intermediate stiffness between that of the midfoot 52 and the greater flexibility of the forefoot 60 further toward the toe area 38 than the tongue 64. Moreover, the shape of the tongue 64 is believed desirable in that it tends to conform to the weight distribution of a user's foot when wearing the shoe 24. Thus, the intermediate stiffness provided by the tongue 64 is distributed substantially along the head of the metatarsals in a manner that stabilizes the user when walking in the shoe 24.

For at least the upper 50% of the length forefoot 60 from the toe tip 72 of the insole towards the midfoot 52, the insole 28 is attached directly to the upper surface 68 of the outer sole 36 (or possibly attached to an intermediate layer which does not substantially increase the rigidity of the upper 50% of the forefoot 60, e.g., the bending force (for bending the shoe sole 20 30 degrees along the flexline 66, FIG. 1) is generally below 50% of the force required to bending the shoe at, e.g., at the commencement of the width reduction portion of the innersole 32, i.e., commencement of the tongue 64). Accordingly, at least the majority of the forefoot 60 is extremely flexible in that the insole 28 is made of, preferably, an extremely flexible and foot conforming material such as ethylene vinyl acetate (EVA) or a layer of latex, and the only additional layer that may be provided between the upper surface 68 of the outer sole and the insole 28 is a layer of glue for bonding the two insole and outer sole together. Note that in other prior art shoe construction techniques, there is at least two adhesive bonding layers and/or a stiffening member inserted between the insole 28 and the outer sole 36 for maintaining the structural integrity of the toe area of the forefoot 60 of the sandal 24. However, in the shoe construction disclosed herein, such additional bonding layers and stiffening member in the area generally spanning the width of the shoe through the toe area 38 to the shoe toe tip 72 are not necessary, and indeed undesirable.

Referring again to FIG. 2, it can be seen that the sandal 24 disclosed therein has sandal straps 70 and 74 for retaining the user's foot on the insole 28 while wearing the sandal. In particular, the sandal straps 70 and 74 are attached to the sole 20 by preferably gluing the straps between the upper surface 68 of the outer sole 36 and the facing surface of either the innersole 32 or the insole 28 contacting (and attached to) the upper surface 68. Thus, for the straps 70, these straps are glued between the outer sole 36 and innersole 32. However, for at least some of the straps 74, these straps are glued between the outer sole 36 and the insole 28 since there is no intermediate layer therebetween.

Referring now to FIGS. 4A-4D, alternative embodiments for the shape of the innersole (more particularly, the base 40) are shown. FIG. 4A shows a full the silhouette of the innersole 32R as described except that is for a right-footed shoe rather than a left-footed shoe as shown in FIGS. 1-3. FIG. 4B shows a full the silhouette of the innersole 32.1R for a right-footed shoe, wherein two cutouts 78 are provided in the center of the tongue 64 for reducing the stiffness of the tongue. Note that the side cutouts 82 may be reduced in comparison to the corresponding cutouts in the innersole 32 of FIGS. 1-3. FIG. 4C shows a full the silhouette of the innersole 32.2L for a left-footed shoe, wherein the side cutouts 82 are reduced in comparison to the corresponding cutouts in the innersole 32 of FIGS. 1-3, and a plurality of cutouts 86 are distributed across the tongue 64 in a manner where there is greater amount of the tongue removed toward the outside edge of the innersole than toward the inside edge. FIG. 4D shows a full the silhouette of the innersole 32.2L for a left-footed shoe, wherein the side cutouts 82 are reduced in comparison to the corresponding cutouts in the innersole 32 of FIGS. 1-3, and there are a plurality of hole cutouts provided in the tongue 64 to thereby reduce its stiffness.

Moreover, in another embodiment, the innersole may extend without cutouts by making the innersole thinner as the innersole extends toward the shoe toe tip 72. That is, the innersole surface area may substantially match the surface area of the insole and/or outer sole throughout the foot contacting area of the insole, but the innersole becomes progressively thinner (and likely ends near or just beyond the flexline) thereby, again, reducing the stresses on the user's foot when the shoe is bent, e.g., at the flexline. Accordingly, in all embodiments disclosed herein, there is a reduction in the quantity of innersole stiffening material making up the innersole as the innersole extends, e.g., near to and beyond the flexline.

In FIG. 5 a high level flowchart is shown describing the steps performed in manufacturing a shoe as described hereinabove. Accordingly, in step 404, the base 40 of the innersole 32 (or one of the other innersole embodiments of FIGS. 4A-4D) is formed from, e.g., cardboard or fiberboard. The base 40 may be stamped or cut from a relatively large sheet of the cardboard or fiberboard. In step 408 a shank 40 is attached to the base 40 by rivet, glue, or other well known attachment means. Then in step 412, a corresponding insole 28 and outer sole 36 are aligned with the innersole formed in steps 404 and 408, wherein the innersole is sandwiched between the insole 28 and the outer sole 36 such that the shank 44 is facing the outer sole. In step 416, a foot covering material is provided in alignment with the members of the sole 20 aligned together in step 412. In particular, for the shoe 24 of FIG. 2, the strap 70 that attaches to the sole 20 may be inserted between the innersole 32 and the outer sole 36. Similarly, the straps 74 closest to the strap 70 may be also be inserted between the innersole 32 and the outer sole 36. However, for at least the strap 74 closest to the toe tip of the shoe 24, since there is no portion of the innersole 32 where this strap attaches to the sole 20, this strap cannot attach to the innersole 32. Note that in the present step, glue may be provided on the end portions of the straps 70 and 72 (or on the portions of the sole 20 layers that the end portions contact) for securing the straps to the sole 20.

In step 420, the foot covering material and the members of the sole 20 are affixed together by, e.g., applying pressure to any items to be secured together by glue, and/or stitching together any items to be secured by such stitching.

In an alternative embodiment, for manufacturing a shoe according to the present disclosure, the steps 412 and 416 may be substantially combined into a single (automated) process. Moreover, note that the foot covering material may provide a closed toe shoe, a man's shoe, a child's shoe, etc.

The foregoing description of the disclosure has been presented for purposes of illustration and description. Further, the description is not intended to limit the present disclosure to the form disclosed herein. Consequently, variation and modification commiserate with the above teachings, within the skill and knowledge of the relevant art, are within the scope of the present disclosure. In particular, novel aspects described hereinabove may be used in closed toe shoes, men's shoes, and children's shoes. The embodiment described hereinabove is further intended to explain the best mode presently known of practicing the invention claimed hereinbelow, and to enable others of ordinary skill in the art to utilize the claimed invention as such, or in other embodiments, and with the various modifications required by their particular application or uses of the invention. 

1. A shoe comprising: a shoe sole including: an insole, an innersole, and an outer sole secured together, each having corresponding widths traverse to a length of the shoe; wherein the innersole is secured between the insole and the outer sole, the insole contacts a person's foot wearing the shoe, and the outer sole contacts the ground when the person walks in the shoe; wherein the innersole includes a first portion having a length that extends from a heel portion of the shoe towards a distal end of the shoe's length, wherein the first portion has a width substantially coincident with the insole's width throughout the length of the first portion, and the first portion is for stiffening the shoe; wherein the innersole includes a second portion extending from the first portion and toward the distal end, wherein the second portion has one or more cutouts for reducing a stiffness of the shoe in proximity to a flexline of the person's foot when the shoe is fitted thereon. reduced quantity of innersole stiffening material across the second portion's corresponding innersole widths in comparison to corresponding shoe's width; wherein the reduced quantity of material second portion provides an intermediate flexibility between a rigidity of the portion of the sole having the first portion, and a more flexible portion of the sole extending beyond the innersole to at least the toe area where the insole is secured directly to the outer sole substantially throughout the more flexible portion.
 2. The shoe of claim 1, wherein the one or more cutouts are positioned so that there more innersole stiffening material removed more toward the outer walking edge than on the inner walking edge of the shoe.
 3. The shoe of claim 1, wherein the reduced width on the outer walking edge is approximately 60% to 70% of the reduction in width of the reduced width.
 4. The shoe of claim 1, wherein the extent of the second portion in a direction of the shoe length is approximately three-quarters of an inch to one and three-quarters of an inch.
 5. The shoe of claim 1, wherein the extent of the second portion in a direction of the shoe length is in a range of 6% to 10% of the shoe length.
 6. The shoe of claim 1, wherein the extent of the second portion in a direction traverse to the shoe length is approximately 20% to 33% of a corresponding width of the insole.
 7. The shoe of claim 1, wherein a length of the innersole is in a range of approximately 78% and 85% of the total length of the shoe sole.
 8. The shoe of claim 1, wherein a length of the first portion in a direction of the shoe length is in a range of between 65% and 78% of the total shoe length.
 9. The shoe of claim 1, wherein the first portion includes a shank that extends no further, in a shoe length direction, than within one-eighth of an inch of a boundary between the first portion and the second portion.
 10. The shoe of claim 1, wherein for at least 50% of a forefoot length of the shoe from a tip of the shoe at a toe end thereof, insole 28 is attached directly to the outer sole.
 11. The shoe of claim 1, further including a shoe layer residing in a forefoot area of the shoe between the insole and the outer sole, wherein the insole is attached to the shoe layer, and the shoe layer does not increase a bending force along a flexline of the shoe above 50% of a force for bending the shoe at a boundary between the first portion and the second portion.
 12. A method for manufacturing a shoe comprising: providing an insole, an outer sole for the shoe, and a foot covering for securing the shoe to a user's foot; obtaining an innersole for the shoe, wherein the innersole includes a first portion having a length that extends from a heel for the shoe towards a distal end of the shoe, wherein throughout the length, the first portion has a width substantially coincident with a width of an insole for the shoe; wherein the innersole includes a stiffening portion cut or stamped from a substantially planar material for stiffening the shoe, the stiffening portion including a first portion having a length that extends from a heel portion of the shoe towards a distal end of the shoe's length, wherein the first portion has a width substantially coincident with the insole's width throughout the length of the first portion, and the first portion is for stiffening the shoe; wherein the stiffening portion includes a second portion extending from the first portion and toward the distal end, wherein the second portion includes reduced quantity of innersole stiffening material across the second portion's corresponding innersole widths in comparison to the first portion; wherein the reduced quantity of material second portion provides an intermediate flexibility between a rigidity of the portion of the sole having the first portion, and a more flexible portion of the sole extending beyond the innersole to the toe area of the shoe; and affixing the innersole and at least one portion of the foot covering between the insole and the outer sole of the shoe, wherein the at least one portion of the foot covering is not layered above or below the innersole.
 13. A shoe comprising: a shoe sole including: an insole, an innersole, and an outer sole secured together, each having corresponding widths traverse to a length of the shoe; wherein the innersole is secured between the insole and the outer sole, the insole contacts a person's foot wearing the shoe, and the outer sole contacts the ground when the person walks in the shoe; wherein the innersole includes a stiffening portion cut or stamped from a substantially planar material for stiffening the shoe, the stiffening portion including a first portion having a length that extends from a heel portion of the shoe towards a distal end of the shoe's length, wherein the first portion has a width substantially coincident with the insole's width throughout the length of the first portion, and the first portion is for stiffening the shoe; wherein the stiffening portion includes a second portion extending from the first portion and toward the distal end, wherein the second portion includes reduced quantity of innersole stiffening material across the second portion's corresponding innersole widths in comparison to the first portion; wherein the reduced quantity of material second portion provides an intermediate flexibility between a rigidity of the portion of the sole having the first portion, and a more flexible portion of the sole extending beyond the innersole to the toe area of the shoe; and a foot covering for covering a top portion of the person's foot when the person is wearing the shoe, wherein the foot covering is operably affixed to the shoe sole. 